ffc team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Sun, Nov 20, 2011 at 07:48:19PM +0100, Marie E. Rognes wrote:
> On 11/20/2011 07:29 PM, Garth N. Wells wrote:
> >I'm trying to track down a bug that leads to a silent failure. I'm as
> >far as a call to the FFC function
> >
> >    ffc.tensor.estimate_cost
> >
> >which fails to return. This function is called from the function
> >
> >     ffc.analysis._auto_select_representation
> >
> >What I don't get is why it's even being called. Since the code that
> >I'm running is:
> >
> >    from dolfin import *
> >    mesh = UnitSquare(32, 32)
> >    V = FunctionSpace(mesh, "Lagrange", 1)
> >    print "------------- end"
> >
> >It's only a FunctionSpace, so why is FFC going through code that is
> >for analysing forms?
> >
> >
>
>
> Because of the use of a dummy form for generating function
> spaces, see def jit_element(...) in ffc/jitcompiler.py.
>
> This has already resurfaced recently, cf
>
>     https://bugs.launchpad.net/dolfin/+bug/884670

Not going via the form jit compiler would require some refactoring of
the jit code in FFC. This would be good to do in the long run, but I
don't think it's a good idea to do at the moment since the jit chain
is complex, fragile and error prone. Changes would likely introduce
bugs.

Do you have an example of a form that hangs ffc.tensor.estimate_cost?
It should be easy to debug.

--
Anders